LOW-COST AUTOMATED FIBER PIGTAILING MACHINE

At present, the high cost of optoelectronic (OE) devices is caused in part by the labor-intensive processes involved with packaging. Automating the packaging processes should result in a significant cost reduction. One of the most labor-intensive steps is aligning and attaching the fiber to the OE device, the so-called pigtailing process. The goal of this 2-year ARPA-funded project is to design and build 3 low-cost machines to perform sub-micron alignments and attachments of single-made fibers to different OE devices. These Automated Fiber Pigtailing Machines (AFPMs) are intended to be compatible with a manufacturing environment and have a modular design for standardization of parts and machine vision for maximum flexibility. This work is a collaboration among Uniphase Telecommunications Products (formerly United Technologies Photonics, UTP), Ortel, Newport/Klinger, the Massachusetts Institute of Technology Manufacturing Institute (MIT), and Lawrence Livermore National Laboratory (LLNL). UTP and Ortel are the industrial partners for whom two of the AFPMs are being built. MIT and LLNL make up the design and assembly team of the project, while Newport/Klinger is a potential manufacturer of the AFPM and provides guidance to ensure that the design of the AFPM is marketable and compatible with a manufacturing environment. The AFPM for UTP will pigtail LiNbO{sub 3} waveguide devices and the AFPM for Ortel will pigtail photodiodes. Both of these machines will contain proprietary information, so the third AFPM, to reside at LLNL, will pigtail a non-proprietary waveguide device for demonstrations to US industry

Using the Heterodyne Method to Measure Velocities on Shock Physics Experiments

We developed a velocimeter system several years ago that uses the heterodyne method [1]. This system is assembled from commercially available components that were developed for the telecommunications industry. There are several advantages of this system over the traditional VISAR method that has made it increasingly popular. This system is compact, portable, and relatively inexpensive. The maximum velocity of this system is determined by the electrical bandwidth of the electronics and the digitizer sample rate. The maximum velocity for the system described here is over 5 km/s

PDV Probe Alignment Technique

This alignment technique was developed while performing heterodyne velocimetry measurements at LLNL. There are a few minor items needed, such as a white card with aperture in center, visible alignment laser, IR back reflection meter, and a microscope to view the bridge surface. The work was performed on KCP flyers that were 6 and 8 mils wide. The probes used were Oz Optics manufactured with focal distances of 42mm and 26mm. Both probes provide a spot size of approximately 80?m at 1550nm. The 42mm probes were specified to provide an internal back reflection of -35 to -40dB, and the probe back reflections were measured to be -37dB and -33dB. The 26mm probes were specified as -30dB and both measured -30.5dB. The probe is initially aligned normal to the flyer/bridge surface. This provides a very high return signal, up to -2dB, due to the bridge reflectivity. A white card with a hole in the center as an aperture can be used to check the reflected beam position relative to the probe and launch beam, and the alignment laser spot centered on the bridge, see Figure 1 and Figure 2. The IR back reflection meter is used to measure the dB return from the probe and surface, and a white card or similar object is inserted between the probe and surface to block surface reflection. It may take several iterations between the visible alignment laser and the IR back reflection meter to complete this alignment procedure. Once aligned normal to the surface, the probe should be tilted to position the visible alignment beam as shown in Figure 3, and the flyer should be translated in the X and Y axis to reposition the alignment beam onto the flyer as shown in Figure 4. This tilting of the probe minimizes the amount of light from the bridge reflection into the fiber within the probe while maintaining the alignment as near normal to the flyer surface as possible. When the back reflection is measured after the tilt adjustment, the level should be about -3dB to -6dB higher than the probes specified back reflection. This 3 to 6dB increase in back reflection from the surface relative to the probes specified back reflection is the optimal level for acquiring data from the flyer. Data obtained with the LLNL system is shown in Figure 5

Embedded Fiber Optic Probes to Measure Detonation Velocities Using the Photonic Doppler Velocimeter

Detonation velocities for high explosives can be in the 7 to 8 km/s range. Previous work has shown that these velocities may be measured by inserting an optical fiber probe into the explosive assembly and recording the velocity time history using a Fabry-Perot velocimeter. The measured velocity using this method, however, is the actual velocity multiplied times the refractive index of the fiber core, which is on the order of 1.5. This means that the velocimeter diagnostic must be capable of measuring velocities as high as 12 km/s. Until recently, a velocity of 12 km/s was beyond the maximum velocity limit of a homodyne-based velocimeter. The limiting component in a homodyne system is usually the digitizer. Recently, however, digitizers have come on the market with 20 GHz bandwidth and 50 GS/s sample rate. Such a digitizer coupled with high bandwidth detectors now have the total bandwidth required to make velocity measurements in the 12 km/s range. This paper describes measurements made of detonation velocities using a high bandwidth homodyne system

A Novel System for High-Speed Velocimetry Using Heterodyne Techniques

We have built a high-speed velocimeter that has proven to be compact, simple to operate, and fairly inexpensive. We assembled our velocimeter using off-the-shelf components developed for the telecommunications industry. The main components are fiber lasers, high-bandwidth high-sample-rate digitizers, and fiber optic circulators. The laser is a 2-watt CW fiber laser operating at 1550 nm. The digitizers have 8-GHz bandwidth and can digitize four channels simultaneously at 20 GS/s. The maximum velocity of our system is approximately 5000 m/s and is limited by the bandwidth of the electrical components. For most of our applications, we analyze the recorded beat frequency using Fourier transform methods, which determines the time response of the final velocity time history. We generally analyze our data with approximately 50 ns Fourier transform windows. We have obtained high-quality data on many experiments such as explosively driven surfaces and gas gun assemblies